revised no certificate state for dashboard messages and removed course message UI for future work on separate branch

* Save errors for courses that failed to load in modulestore
* global staff can see course errors on their dashboard
* put policy loading errors into the error trackers
* add has_access(user, 'global', 'staff'), which is equiv to user.is_staff for now

* All access control logic is now in access.py
* It exports a single method for general use: has_access(user, object, action)
 - possible actions depend on object type (e.g. 'see_exists', 'enroll', 'staff')
* Removed DARK_LAUNCH feature flag--it is now the default behavior
* Replaced check_course with three separate more focused functions that use has_access

Minor things:
* note on using pdb in testing
* moved time parsing helper into timeparse.py
* x_modules now have a .start attribute (None if not in metadata)

Registering now temporarily logs you in. A message is displayed on the dashboard, reminding you to activate your account. Logging in shows a reminder about activating.

Now displaying full name on the dashboard, instead of location. The icon is just a generic info icon, for now.

fixes title of course in dashboard to accept very long course names, improves various other UI elemnts in the dashboard

Added {COURSE_STATIC_URL} format key for about section html. Changed get_about_section to be get_course_about_section in courseware.courses.

renames some scss files for better orginization, sets fixed widths on main containers to avoid akward scaling issues untill media queries can be added for more responsive scaling

cleans up home page header design, adds social sharing to header, adds tos, privacy policy, honor code, help and copyright pages, add liks to those pages in footer, finished contact page

Signing in brings you to your dashboard instead of the courses page with a find courses button when not enrolled.